I lived in Milan as a kid, when Malpensa was new. It seems to me the designers chose the place in Northern Italy with the worst weather (fog, snow, they all congregate on Malpensa). A rough translation from the Italian of 'Mal pensa' is 'Bad thought'. I always try to get a flight into Linate when I'm revisiting my former home town, at least there's a reasonable chance of it being open.
I suppose that the Italian/Regional govt had few choices as to where to build an airport capable of expanding. As an ex-resident you will no doubt recall the depressing 'nebbia' that befalls Milano each year and Linate was certainly no stranger to it and consequent disruptions. That said Linate is/was close enough to get to by bus, or the wonderful taxis with all their 'supplimentos'. I once had 6 extra charges on my journey of 9kms! I think that Linate even without the fog and close location to the city would have made a hard candidate to expand due to the motorway and lakes close by. When I lived in Milan in the 90's getting to Malpensa was not the dream that it is now, it was by coach on small country roads and the airport definitely had the vacant air of Stansted in the 70/80's. I quite liked it, but progress dictates that things move on.